There have been wheelchairs and carrier carts available as electric vehicles which are propelled by means of a drive unit.
Some electric vehicles have an alarm unit which, using sound or light, notifies an operator of information on low power of a battery unit to supply power to a drive unit. Some electric vehicles have an alarm unit which, using sound or light, notifies an operator of information on an obstacle detected ahead in a traveling direction by a sensor.
However, when such information on low battery or detection of an obstacle is sent to an operator using light, the operator may overlook the information because the light is emitted incidentally out of sight of the operator. When such information is sent to an operator using sound, the operator may miss the information because the electric vehicle is incidentally traveling in a noisy place. It is therefore desired that electric vehicles be provided which send operators information by means other than sound or light.
Although this is not a technique for electric vehicles such as a wheelchair and a carrier cart, there is a proposed braking force control device 1 for motor vehicles which provides a driver with haptic information using vibration of a vehicle body caused by actuating the brake of the vehicle in a certain pattern (see Patent Literature (PTL) 1).
FIG. 21 is a system configuration diagram of the conventional braking force control device 1 for motor vehicles.
As shown in FIG. 21, the braking force control device 1 has a control unit 2 including a judgment means 3 and an alarming means 4. The judgment means 3 judges, from a result of detection by a radar device 5, whether or not contact with an obstacle is evitable. When the judgment means 3 judges that there is a danger of the vehicle contacting with an obstacle, the alarming unit 4 alarms a driver using a warning image or a warning sound. The alarming unit 4 also alarms a driver by applying a pulsative braking force (warning brake) to slow the motor vehicle and generate vibration to be perceived by the driver.
When the alarming unit 4 gives a driver a haptic alarm by applying such warning brake, the alarming unit 4 issues a braking instruction to a brake control unit 6 to activate a brake actuator 7 so that a braking force is generated by pulsatively actuating a brake 8, which is a braking means. The vehicle is then vibrated by the braking force, so that the driver notices that there is a danger of the motor vehicle contacting with an obstacle.
In this configuration, when the motor vehicle disclosed in PTL 1 detects an obstacle with which the vehicle may contact, the vehicle activates a brake so that the vehicle can decelerate and give the driver a haptic alarm.